Lumber-drier.



A. D. LINN. LUMBER nmrm. APPLICATION IILBD NOV. 8, 1909. RENEWED JULY 23,1912.

Patented Mar. 11, 1913.

I I I I, fjwuel M 07 anal/ nu Hum wi/immeo ITED sTAT s PATENT OFFICE.

ALLEN D. LINN, 0F GRAND RAPIDS, MICHIGAN.

LUMBER-DRIER.

Patented Mar. 11,1913.

Application filed November 8, 1909, Serial No. 527,015. Renewed July 23, 1912. Serial No. 711,192.

To all whom it may concern:

Be it known that I, ALLEN D. LINN, a citizen of the United States, residing at Grand Rapids, in the county of Kent and State of Michigan, have invented certain new and useful Improvements in Lumber- Driers, of which the following is a specification.

My invention relates to improvements in kilns for drying lumber, and its objects are: first, to provide a means whereby I can avert the danger of checking the surface or ends of the lumber, both when first applying heat to the cold lumber as it is entered into the kiln, and when cooling the seasoned lumber preparatory to removing it from the kiln, and, second, to provide a means whereby the steam in the coils will be readily condensed and the circulation and return to the source of supply greatly facilitated and by the same process that averts the danger of checking the lumber while fitting it in the kiln preparatory to removing it therefrom. I attain these objects by the mechanism illustrated in the accompanying drawing, in which- Figure 1 is a sectional elevation of a kiln on the line w m of Fig. 2, andl ig. 2 is a sectional elevation of the same on the -line y y of Fig. 1, with a portion of the front wall of the heating chamber cut away to show the position of the coils and the circulation of cold air into and through this chamber and thence into the kiln.

Similar letters refer to similar parts throughout the several views.

It has been the universal result, especially when attempting to season lumber that has been partly dried in the open atmosphere, that the ends and surfaces of the lumber will check and greatly reduce the value of the lumber for manufacturing purposes, when heat is made to circulate around and over it. To avert this danger I have found that the most effectual means is to expose it to a liberal sweating with saturated steam allowed to flow directly into the kiln and come in contact with every portion of the surface of the lumber, and to thus expose it until the lumber has become pretty generally saturated with the moisture from such steam, or, in other words, until the surface of the lumber has become thoroughly softened, after which the lumber must be exposed to a gradually increasing temperature with the humidity diminishing as the temperature increases, until it has reached the desired height and dryness of temperature, where itshould be held until the lumber has been exhausted of all the moisture that can be, practically, forced from it. When the lumber has reached this stage, which usually requires several days of exposure to heat, &c., it must be removed from the kiln, a process that must be very carefully provided for to avoid the danger of checking the surface and ends of the heated lumber by sudden exposure to a cold atmosphere, either by opening the kiln and allowing the atmosphere to come in volume in direct contact with the hot lumber, or by entering the atmosphere through ducts in the walls of the kiln, directly above, and upon the lumber. Another, and a very damaging result that follows from the process of cooling of the lumber by allowing a current of atmospheric air to enter the kiln by means of ducts through the walls, directly upon the lumber, .is that the moisture in the atmosphere is forced into the surface of the lumber and saturates to such an extent as to make it practically unfit for use by reason of the danger of shrinkage after it has been manufactured and'the manufactured article has been finished and placed upon the market.

To avert these difficulties, I construct my kilns upon practically the plan shown in the drawings, in which- A represents one end wall, A, another end wall and C a curtain between two compartments in the kiln.

B B represent the side walls of the kiln, F, a grated floor, and F a compact floor for the kiln proper, and below these floors I form two chambers. One of these chambers is beneath the grated floor F and is designed to hold the large steam coil G.

In the process of drying lumber the lumber is run into the chamber of the kiln above the grated floor F and this chamber or compartment is closed and a jet of live, saturated steam, as at the valve 1), is allowed to escape into the compartment and directly upon and around the lumber D, and the temperature of the compartment is gradually raised by the radiation of heat from the coils G, as indicated by the full line arrows in this compartment, the heated atmos here escaping through any available form o. flue, as indicated at I), while cold air entering the compartment, or escaping from the lumber, is carried off through the flues represented at a, as indicated by the dotted outlines of arrows passing from the lumber to and through these fiues, the draft in whlch 1S facilitated by the heat radiated from the vertical pipes'indicated at 2 lVhen the lumber D has become sufficiently saturated and heated by the application of live steam, as hereinbefore stated, the steam at the valve 6 is shut off and only the heat radiated from the coil G is allowed to act upon the lumber until it has become thoroughly dried, when it may be passed into the second chamber, as at D, and the curtain C closed to prevent the passage of heated or steam 1mpregnated atmosphere from passing from one to the other. The lumberis now in what may be called the finishing and dryingchamber. Ordinarily, my process from this stage is to allow a current of atmospheric air to enter directly into the kiln above the lumber, which has the double inclination, hereinbefore mentioned, first, of suddenly chilling the lumber and causing it to check, and, secdnd, of saturating the surface of the lumber with the latent moisture in the infiowing atmospheric air, and rendering it unsafe for immediate use in manufactured articles. I avert these difliculties by placing a wall, H, in thelower compartment of the kiln, thus forming a second coil chamber for the inclosure of the coil H. This must be small enough to utilize all the heat that is radiated from the coil H for raising the temperature of the air as it enters the openings I I, passes through this chamber and, thence, up through the flues represented at a, which discharge into the compartment that contains the lumber D. By this means, the air entering at the openings I I, passes into the kiln at a' much cooler than the air that already fills the kiln, which causes it to settle downward around and over the lumber and to seek a passage out of the duct or fine I), orits equivalent, and, yet, it is sufiiciently heated to avert the danger of checking the lumber or of carrying too much moisture to the lumber, thus avoiding, both, the danger of checking the lumber by reason of too suddenly cooling its surface, and of moistening the surface of the lumber by reason of extreme humidity in the air as it reaches the lumber. Another great advantage gained by passing the cold air from the outer atmosphere to the coils H is to suddenly condense the steam in the coils and cause it to flow out of the spout h, or its equivalent, preferably leading to the steam plant from which the steam is derived, through the pipe 9 to the coil G, thus lessening the pressure in the coils H and inducing the steam from the coils G to be exhausted -more freely, ahdproducing a much better circulation throu h the coils than could, otherwise be prodlloed. i

The wall shown at F acts a double purpose, first, as a support for the ways, tracks or grating that supports and carrles the lumber, and, second,it forms a division wall continuous with the curtain 'C to prevent steam from passing from one chamber into the other, and the solid portion, F, of the floor is designed to make the chamberthat inclose s the coil H a separate-chamber from theone inclosing the coil G, and to form the fine f for the passage of air from thischamber to the flue a.

It'will be readily understood that with the ourtain C raised to the position indicated at C the kiln would be composed of a single compartment, in which case, to consummate the drying of lumber by my process, it would be necessary. simply, to close the flues or openings I with the door i, so that no air could reach or enter the chamber that contains the coil H, while the lumber is being exposed to the direct action of steam, and in its succeeding stages up to the time when it is desired to prepare it to be removed from the kiln, and ,athis time the steam should be cut off and the' doors 2' opened so that the atmospheric air may be allowed to enter, with the same results as have been hereinbefore described.

lVith the kiln divided into two compartments, as indicated'by the partitioning'curtam 1n Fig. 1, the process is that known as drying lumber in a progressive kiln. That is, the lumber is partly dried in one compartment where the saturated steam is applied, andremoved to the other compare compartment. as indicated by the drawn curtain at C, it is called a box kiln. That is, the lumber is first exposed to the direct action of saturated steam, after which the free steam is gradually turned off and a higher degree f dry heat is used in the same compartment, and, finally, when the desired amount of moisture is extracted from the lumber, it is exposed to a current of previously heated atmospheric air, in the same compartment, thus being carried through the several stages without change of position.

The object of placing the heating coil 5 in. the vertical portion of the fine a is to 'form a forced draft through this fine, strong enough to draw the cooler air, air impregnated with the acids from the drying lumber, or other material being dried, and the moisture being forced from the material being dried. downward to the opening to the horizontal portion of this flue and thence out to the open atmosphere at or near the top of the kiln.

What- I claim as new, and desire to secure by Letters Patent of the United States, is:

1. In a kiln for drying lumber, walls in closing a compartment for storing lumber and a compartment for a steam coil, a steam coil so placed that saturated steam may be discharged into the lumber compartment, a'

' carry the moist air out of the kiln.

2. In dry kiln construction, lumber drying compartments, steam coils below said compartments, an open steam jet arranged to discharge in one of said compartments, a closed chamber under the other of said compartments, a continuation of the steam coil in said compartment, 'flues leading from the outer atmosphere to said compartment and fiues leading from this compartment to the upper portion of the kiln and discharging therein, so that atmospheric air may be passed over the coil to condense steam therein, and to heat the air before carrying it into the kiln, and fines leading from the kiln to insure perfect circulation.

' 3. In dry kiln construction, walls inclosing a lumber drying compartment and a compartment for steam coils, a steam coil in said compartment, a steam pipe leading to said coil, a valve on said pipe arranged to open for a flow of saturated steam into the lumber compartment and to be gradually closed while the degree of heat is being raised in the lumber compartment, the walls of the coil compartment having openings for conducting air into the coil compartment, the walls of the kiln having fines for conducting the hot air from the coil compartment into the kiln above the lumber, and .flue's for conducting the moist air out of the bottom of the kiln up through the Wall and out to the open air.

Signed at Grand Rapids Michigan November 4, 1909.

ALLEN D. LINN. In presence of-- I. J. CILLEY, A. ALLGIER. 

